天然吩嗪化合物的生物合成

吩嗪化合物种类繁多,天然吩嗪化合物多具有广谱的抗菌、抗肿瘤活性,在医药、农业等领域有着广泛的应用.天然吩嗪化合物主要由假单胞菌和链霉菌等微生物产生,而莽草酸代谢途径、莽草酸代谢替代途径和吩嗪修饰途径为普遍公认的吩嗪的生物合成途径.     

利用重组大肠杆菌合成莽草酸的研究进展

莽草酸是芳香族氨基酸合成途径中的一种重要中间代谢产物。近年来,莽草酸作为临床上对抗禽流感的惟一有效药物达菲的合成前体而备受关注。通过改造大肠杆菌代谢通路使之能大量积累莽草酸是研究的热点之一。文章综述了莽草酸在重组大肠杆菌中生物合成的途径,并分析了莽草酸合成过程中的关键基因的改造及其对莽草酸积累的影响,最后还讨论了减少莽草酸产生菌培养过程中副产物产成的若干措施。     

若干莽草酸衍生物的合成和生物活性研究

虽然对莽草酸(shikimic acid)的研究由来已久,但只是在陆续发现了具有生物活性的乙二醛酶Ⅰ抑制剂(glyoxalase Ⅰinhibitor 1)和二(口恶)霉素(dioxolamycin 2)等含莽草酸类母核的天然产物后,才有合成莽草酸衍生物进行生物活性研究的报道,即由莽草酸甲酯合成乙二醛酶Ⅰ抑制剂的类似物3。     

莽草酸的研究现状

莽草酸（shikimic acid）,异名毒八角酸,它是可有效对付禽流感病毒和甲型H1N1流感病毒药物＂达菲＂的重要原料。莽草酸通过影响花生四烯酸代谢,抑制血小板聚集,抑制动、静脉血栓及脑血栓形成;其次,莽草酸具有有抗炎、镇痛作用;另外,莽草酸还可作为抗病毒和抗癌药物中间体。     

从八角茴香分离莽草酸的简便方法

莽草酸(shikimic acid)是存在于高等植物或微生物的次级代谢产物。自陆续发现了一些具有生物活性的含莽草酸类结构的天然产物后,对它的衍生物的合成和药理研究已渐引起人们注意[Jung M:J Antibiot 1987,40:720]。为了开展此项研究,作者从市售     

3H-1,2-二氢-2-(4-甲基苯胺基)甲基-1-吡咯里嗪酮在家兔体内主要代谢产物的研究

用高效液相色谱法对家兔单剂量ig750mg新抗炎镇痛剂3H-1,2二氢-2-(4-甲基苯胺基)-甲基-1-吡咯里嗪酮(Z-47)后尿中的代谢物进行了分离、检测。根据代谢物的色谱行为及与Z-47结构有关的其它药物的代谢途径,推测Z-47羧基衍生物[4-(3H-1,2-二氢-1-吡咯里嗪酮-2-甲基胺基)苯甲酸]是一可能的代谢产物,遂用化学方法合成了该衍生物。利用色谱保留值、紫外双波长吸收比值等对代谢物和标准品进行比较,并对尿样的酶水解产物进行色谱分析,证实Z-47羧基衍生物及其酯型β-D-葡糖苷酸结合物是Z-47在家兔体内的主要代谢产物。     

3H－1，2－二氢－2－（4－甲基苯胺基）甲基－1－吡咯里嗪酮在家兔体内主要代谢产物的研究

用高效液相色谱法对家兔单剂量ｉｇ７５０ｍｇ新抗炎镇痛剂３Ｈ－１，２二氢－２－（４－甲基苯胺基）－甲基－１－吡咯里嗪酮（Ｚ－４７）后尿中的代谢物进行了分离、检测。根据代谢物的色谱行为及与Ｚ－４７结构有关的其它药物的代谢途径，推测Ｚ－４７羧基衍生物［４－（３Ｈ－１，２－二氢－１－吡咯里嗪酮－２－甲基胺基）苯甲酸］是一可能的代谢产物，遂用化学方法合成了该衍生物。利用色谱保留值、紫外双波长吸收比值等对代谢物和标准品进行比较，并对尿样的酶水解产物进行色谱分析，证实Ｚ－４７羧基衍生物及其酯型β－Ｄ－葡糖苷酸结合物是Ｚ－４７在家兔体内的主要代谢产物。     

伊立替康体内代谢途径及代谢产物的研究进展

目的综述伊立替康体内代谢途径和代谢产物的研究进展。方法检索国内外关于伊立替康及其代谢产物体内代谢途径的文献和资料,进行综述。结果和结论伊立替康具有非常复杂的体内代谢特征,在体内外受羧酸酯酶、葡萄糖醛酸转移酶、细胞色素P450和β-葡萄糖苷酸酶影响,代谢物之间可以相互转化,对于伊立替康的临床治疗有一定指导意义。     

氯霉素生产的优化与遗传

氯霉素是由委瑞拉链霉菌产生的。氯霉素生物合成、调节和遗传已研究得相当详细。含乳酸、甘油和丝氨酸合成培养基生产氯霉素约150mg/升。加入芳香氨基酸能刺激氯霉素生产。即使乳酸代谢差,但它对于氯霉素生产是很需要的。大概培养基内乳酸使内源合成丙酮酸转向莽草酸途径。     

液相色谱-电喷雾离子阱质谱法研究人尿中1,5-二咖啡酰奎宁酸的代谢产物

目的 研究健康受试者口服1,5-二咖啡酰奎宁酸后尿液中的代谢产物.方法 健康受试者每人口服1,5-二咖啡酰奎宁酸600 mg,收集0-24 h的尿样,经C_(18)小柱固相萃取纯化后,用液相色谱-电喷雾离子阱质谱联用技术对人尿中的代谢产物进行分析鉴定.结果 在人尿中发现了1,5-二咖啡酰奎宁酸的甲基化、葡萄糖醛酸化及甲基-葡萄糖醛酸化代谢产物共28个.其中,有2个代谢产物结构经标准品对照得到确证.结论 甲基化、葡萄糖醛酸化和异构化反应是1,5-二咖啡酰奎宁酸在人体内的3种重要代谢途径.     

Multi-dimensional visualization for the morphology of lubricant stearic acid particles and their distribution in tablets

The shapes of particles and their distribution in tablets, controlled by pretreatment and tableting process, determine the pharmaceutical performance of excipient like lubricant. This study aims to provide deeper insights to the relationship of the morphology and spatial distribution of stearic acid(SA) with the lubrication efficiency, as well as the resulting tablet property. Unmodified SA particles as flat sheet-like particles were firstly reprocessed by emulsification in hot water to obtain the reprocessed SA particles with spherical morphology. The three-dimensional(3 D) information of SA particles in tablets was detected by a quantitative and non-invasive 3 D structure elucidation technique, namely, synchrotron radiation X-ray micro-computed tomography(SR-μCT). SA particles in glipizide tablets prepared by using unmodified SA(GUT), reprocessed SA(GRT), as well as reference listed drug(RLD) of glipizide tablets were analyzed by SR-μCT. The results showed that the reprocessed SA with better flowability contributed to similarity of breaking forces between that of GRT and RLD. SA particles in GRT were very similar to those in RLD with uniform morphology and particle size, while SA particles in GUT were not evenly distributed. These findings not only demonstrated the feasibility of SR-μCT as a new method in revealing the morphology and spatial distribution of excipient in drug delivery system, but also deepened insights of solid dosage form design into a new scale by powder engineering.     

Synergistic effect of quercetin and quinic acid by alleviating structural degeneration in the liver,kidney and pancreas tissues of STZ-induced diabetic rats: A mechanistic study

The aim of this study was to investigate the synergistic effects of quercetin (QE) and quinic acid (QA) on a STZ-induced diabetic rat model to determine their potential role in alleviating diabetes and its associated complications. In our study design, diabetic rats were treated with single and combined doses of QE and QA for 45 days to analyse their effects on liver, kidney and pancreas tissues. The study result showed that QE and QA treated groups down-regulated hyperglycaemia and oxidative stress by up-regulating insulin and C-peptide levels. Moreover, histological observations of the liver, kidney and pancreas of diabetic rats treated with single and combined doses of QE and QA showed a significant improvement in the structural degeneration. Interestingly, the combination dose of QE and QA (50 mg/kg) exhibited maximum inhibition of the pro-apoptotic protein Bax expression and demonstrate enhancement of the anti-apoptotic protein Bcl-2 expression in the kidney tissues, suggesting a protective role in the kidneys of diabetic rats. Taken together, these results indicates the synergistic effects of QE and QA in ameliorating hyperglycaemia, hyperlipidemia and insulin resistance in diabetic rats and therefore, open a new window of research on the combinatorial therapy of flavonoids.     

水和非水毛细管电泳-电导检测法分离测定水杨酸类药物

目的建立水和非水毛细管电泳-电导法分离水杨酸类药物。方法用未涂层石英毛细管柱(55 cm×50 μm),以10 mmol·L^-1 Tris-30 mmol·L^-1 H₃BO₃(pH 8.0)为运行缓冲液,分离电压为24 kV,进样时间10 s,电导检测法。结果在非水实验条件下,水杨酸(SA)、乙酰水杨酸(ASA)和磺基水杨酸(SSA)得到很好的分离。SA,ASA和SSA的线性范围分别为0.05～100 mg·L^-1,5.0～250 mg·L^-1,0.08～100 mg·L^-1,r均大于0.995。结论应用于阿斯匹林制剂中水杨酸和乙酰水杨酸含量的测定,结果令人满意。与水介质相比,乙醇介质具有更高的灵敏度和分离效率。     

Assuring the quality of intravenous admixture programs.

Several aspects of quality assurance (QA) methods in i.v. admixture programs are discussed, and a basic framework for developing QA programs for admixture services is presented. The objective of QA is to insure that admixture products: (1) are therapeutically and pharmaceutically appropriate to the patient; (2) are free from microbial and pyrogenic contaminants; (3) are free from undesirable levels of particulate or toxic contaminants; (4) contain drugs in correct amounts; and (5) are labeled, stored and distributed under principles of good drug control. Three types of QA criteria bases which may be used as indicators of quality are discussed (resources, facilities and organization; required procedures; end-products or results). Because end-product monitoring has certain limitations in the admixture setting, QA must rely heavily on procedure-centered review methods. General guidelines for developing QA programs are outlined. Adherence to procedure is the key to assuring the quality of admixture products. In developing a QA program, the highest priority should be given to the education and training of admixture personnel, particularly with respect to aseptic technique and pharmaceutical calculations.     

Acetylsalicylic acid metabolites in blood and urine after plain and enteric-coated tablets

Acetylsalicylic acid (ASA) was administered orally as a single dose to 7 healthy male volunteers as plain or enteric-coated (Entrophen) tablets using a crossover design. Blood and urine samples were collected and analysed for ASA metabolites by high performance liquid chromatography. Labile and stable glucuronide conjugates of salicylic acid (SA) were measured in urine after differential hydrolysis with glucuronidase. Plasma kinetic parameters for the ASA metabolites SA and salicyluric acid were not different for the 2 formulations, apart from the delayed appearance after the enteric-coated tablets. Total urinary recovery, and recovery of salicyluric acid and the two SA glucuronides were not different, thus confirming the equivalent bioavailability and metabolite profile of the 2 ASA formulations.     

A phenolic extract from grape by-products and its main hydroxybenzoic acids protect Caco-2 cells against pro-oxidant induced toxicity

Grape/wine industry produces large amounts of by-products, however knowledge on their health-promoting qualities is limited. This study investigated the effects of a grape phenolic extract (GPE) and its phenolic compounds, gallic acid (GA) and syringic acid (SA) on human intestinal Caco-2 cells, directly or after cytotoxicity induced by tert-butylhydroperoxide (t-BOOH). Direct treatment with 0.1–10 μg/mL GPE, or 0.1–10 μM GA and SA produced no major cytotoxic effect, either changes in antioxidant defences (glutathione content, glutathione peroxidase and reductase activities) or protein damage (carbonyl groups). However, 10 μg/mL GPE, 1 and 10 μM GA and 10 μM SA decreased reactive oxygen species (ROS) production.Pre-treatment with GPE, SA and GA at the same concentrations for 20 h showed that 10 μg/mL GPE and 10 μM GA or SA significantly counteracted ROS increase induced by t-BOOH. 10 μg/mL GPE and 1–10 μM GA or 10 μM of SA significantly reduced pro-oxidant-induced cytotoxicity. 1–10 μg/mL GPE, 1–10 μM GA and 10 μM SA significantly recovered both depleted glutathione and enhanced glutathione reductase and peroxidase activities, and reduced protein oxidative damage. Therefore, treatment with realistic concentrations of GPE and its main hydroxybenzoic acids protected Caco-2 cells against induced oxidative stress.     

喹啉酸诱发实验性癫痫作用机制的初步研究

喹啉酸是一种内源性的兴奋性氨基酸,给小鼠每只icv10μl(1g·L~(-1)),可引起典型的实验性癫痫。ip异鹅羔胺激动GABA_A型受体;或ip GABA降解酶抑制剂氨氧乙酸,从而增加CNS中的GABA含量;或ip甲基三唑安定以增强GABA受体的亲和力来高脑中GABA能神经系统的功能,均能减弱或对抗喹啉酸的致惊作用。相反,sc GABA_A型受体拮抗剂荷包牡丹碱;或sc GABA合成和释放抑制剂3-巯基丙酸来降低中枢GABA能神经系统的功能,则能促进喹啉酸的致惊作用.所有这些结果提示.CNS中GABA系统的功能在喹啉酸的致惊机制中可能起调控作用。     

Structure,stability, and antiplatelet activity of O-acyl derivatives of salicylic acid and lipophilic esters of acetylsalicylate

The anti-thrombotic activity of acetylsalicylic acid (ASA) has been shown to be due to specific irreversible acetylation of blood platelet cyclooxygenase. The aim of our study was to investigate the associations between the antiplatelet activities of derivatives of both ASA and salicylic acid (SA), as well as the structure, stability, and molecular properties of these compounds. Homologous series of O-acyl derivatives of salicylic acid (propionyl-, butyrylsalicylic acids, PSA, BSA) and lipophilic dodecyl (C12)-, hexadecyl (C16)-, and cholesteryl acetylsalicylates were synthesized and tested for structure-activity relationships. The molecular properties (heat of formation, molecular surface area, dipole moment) of ASA and SA derivatives obtained by theoretical calculations changed with the increasing length of the acyl or alkyl residue. The inhibition of whole blood platelet aggregation and the reduction in thromboxane (TX) generation by O-acyl derivatives were concentration-dependent and decreased along with increasing the length of acyl chain. These effects correlated with the extent of platelet reactivity and P-selectin expression inhibition in collagen-activated platelets. In contrast to ASA and O-acyl derivatives of SA, none of the lipophilic ASA derivatives had a significant inhibitory effect on platelet aggregation.In conclusion, all SA and ASA derivatives studied under in vitro conditions showed much lower antiplatelet activities than ASA itself, despite their higher affinity to plasma proteins or membrane components and their equivalent ability to acetylate protein free amino groups.We suggest the significance of the carboxylic group, dipole moment, geometry, and size of these pharmaceuticals in their ability to bind to the active site of cyclooxygenase and their antiplatelet efficacy.     

The use of high-performance size exclusion chromatography (HPSEC) as a molecular weight screening technique for polygalacturonic acid for use in pharmaceutical applications

Polygalacturonic acid is a linear carbohydrate polymer of monomeric galacturonic acid. It is commercially available as apple and citrus pectins comprised of a mixture of partially methoxylated and/or amidated polygalacturonic acids with molecular weights ranging from 25 000 to >100 000 Da. Pectin can be chemically or enzymatically hydrolyzed to yield polygalacturonic acid fractions of diverse average molecular weight ranges and polydispersities for a variety of uses. Pectin and polygalacturonic acid are used extensively as gelling agents and stabilizers by the food industry, and have applications as therapeutic, and diagnostic pharmaceutical agents such as the magnetic resonance imaging agent LumenHance®. A simple high-performance size exclusion chromatography (HPSEC) method, employing commonly available non-specialized HPLC instrumentation, is described for use as a rapid molecular weight screening technique to determine the average molecular weight range and polydispersity of polygalacturonic acid intended for use in pharmaceutical formulations. A TosoHaas G3000PWXL HPLC column, 50 mM phosphate buffer (pH≈6.9) mobile phase, and refractive index detection were used. A molecular weight calibration curve was linear for polysaccharide standards of 180–100 000 Da with a coefficient of correlation of 0.999. The method was employed to screen commercially available polygalacturonic acid raw materials for average molecular weight data (M_n, M_w, and M_p) and polydispersity (M_w/M_n).     

Structure-activity relationships of β-hydroxyglutamic acid and its relatives on the excitability of an identifiable giant neurone of african giant snail (Achatina fulica ferussac)

A spontaneously firing giant neurone (the PON, periodically oscillating neurone) was identified in suboesophageal ganglia of Achatina fulica Férussac. Effects of four stereoisomers of β-hydroxy- glutamic acid (BHGA) and their analogues were examined on the PON excitability. Erythro-l- and threo-l-BHGA showed an inhibitory effect on the PON, while erythro-d- and threo-d-BHGA had no effect. The l-configuration being essential for producing the effect. Critical concentrations of erythro-l- and threo-l-BHGA to produce the effect (by the bath application) were respectively 10⁻⁶ 3 × 10⁻⁶kg/l and 3 × 10⁻⁵ 10⁻⁴kg/l. l- and d-glutamic acid, allo-γ-hydroxy-l-glutamic acid, erythro- and threo-β-hydroxy-dl-glutamine and erythro- and threo-β-hydroxy-dl-α-glutamine had no effect at 10⁻⁴ kg/1 on the PON. Of the heterocyclic compounds examined, ibotenic acid (IA), quisqualic acid (QA) and three isomers of tricholomic acid (TA) showed an inhibitory effect. The critical concentrations of IA, QA and TA were respectively 3 × 10⁻⁶ 10⁻⁵kg/1, 10⁻⁵kg/l and 10⁻⁴kg/1. In the chloride-free medium, erythro-l-BHGA, IA and QA (by the microdrop application) showed the same effect as in the physiological state. The PON inhibition caused by these substances was not dependent on chloride ions.